Field of the Invention
This application relates to a fluid flow modification apparatus for modifying the characteristics of a flow field, and to a method of modifying fluid flow.
Description of the Related Technology
There are many situations in which it is desirable to modify the flow of a fluid. Examples include in ventilation and fluid mixing, and for controlling fluid flow around bodies, such as fluid flow around aircraft, fluid flow around motor vehicles and fluid flow in mixing apparatus.
As a particular example, it is important when analyzing fluid flow in a test environment to be able to accurately replicate fluid flow conditions which will be encountered during actual use of a product to be tested. Products to be tested under specific fluid flow conditions vary considerably so flexibility in the ability to modify the fluid flow conditions in the test environment is essential.
It will be appreciated that for some products, providing a suitable test environment for analyzing fluid flow conditions can be very demanding. A particular challenge is encountered, for example, when testing constructional components that will be exposed to fluid flow conditions at the top of tall buildings, such as skyscrapers, or on other high constructional installations, such as bridges and wind turbines. The eddy currents in these situations, in particular, can be extremely difficult to replicate, particularly at a sufficiently small scale to allow a practical test environment to be provided.
Currently, such testing generally involves randomly arranging artefacts within a fluid flow in a wind tunnel to affect the fluid flow in such a way that the real fluid flow conditions can be replicated. Usually, the artefacts used are in the form of projections arranged so that they extend substantially vertically into the fluid flow from a base of the wind tunnel. Deciding on the location and size of the projections, however, involves a complex iterative process which can be time-consuming and unpredictable. Control of wakes arising from artefacts in the test environment is also an important factor. By determining and controlling the location at which various wakes meet, for example, turbulence intensity downstream of the artefact can be affected.
Another consideration is the minimization of the work that is required to be done in the test environment to replicate the fluid flow conditions in real life. Drag, in particular, should be reduced as much as possible to ensure that the work done within the wind tunnel is kept to a minimum, and to enable the tunnel to work at higher wind speeds.
Aside from the difficulties in achieving effective fluid flow modification in a test environment, the extent to which real fluid flow conditions are replicated is often inadequate.